Unfortunately, Marvel’s model is difficult to replicate, unless you’re a single studio fortunate enough to captain a mega-franchise. The issue lies, of course, with licenses. Even Marvel Studios struggled to assemble the Avengers; the Hulk once belonged to Universal, and Iron Man was with New Line. Marvel only had the means with which to win them back after a significant financial pact in 2005, enabling it to declare independence as a studio.

It’s common knowledge that a licence deal struck in ‘94 is the reason we won’t be seeing that deceptively unrealistic proposal – an X-Men/Avengers crossover – any time soon. Fox has thirteen odd years worth of X-Men on the big screen, and Sony’s invested enough in Spider-Man to reboot it from the popular Raimi adaptation with plans for a number of future films. Their roots in these franchises – and their pockets - go deep.
Historically, the only way to eschew such licensing issues is to use characters in the public domain – hence the frequent appearances of Dracula, Frankenstein’s Monster and Sherlock Holmes in popular cinema – or that somewhat trickier proposition; collaborate with another studio. There’s the slim possibility that Fox and Marvel could put aside massive creative differences and storyline continuity in their respective properties to work together, but such partnerships tend to sit uneasily. Freddy vs Jason’s years of development hell began because New Line and Paramount both wanted the licence of the other’s character. Hell, New Line’s subsequent Freddy Vs Jason Vs Ash proposal didn’t make its way out of the starting gate.

Really, Spielberg’s the only guy to have done it with finesse. As the producer of 1988’s Who Framed Roger Rabbit, it was he who was tasked with calling upon the giants of the animation world to bring their characters together in a single movie. And while there were some holdouts - Popeye, Tom and Jerry, Little Lulu, Casper and the Terrytoons never made it – his achievement in bringing together characters from Warner, Fleischer Studios, King Features Syndicate, Felix the Cat Productions, Turner Entertainment and Universal Pictures to star alongside Disney stalwarts was remarkable.

The key was compromise. An agreement was drawn up between Disney and Warner Bros. that Warner’s highest-profile characters should appear to be ‘equal’ to Disney’s; hence the fact Bugs and Mickey appear together, and Daffy and Donald are both depicted as master musicians. Disney faced similar hurdles more recently while trying to collect video game characters for its video game themed Wreck It Ralph, when publishers like Nintendo and Sega began to deliver increasingly specific – and eccentric - requests when it came to Disney’s depictions of their iconic characters. Ever consider how Bowser would drink his coffee? Someone at Nintendo has.

In the case of Roger Rabbit (and this weird anti-drugs cartoon crossover tele-movie from the ‘90s, but let’s not go there) there was a sense of goodwill attached to the project that must have been seductive to Warner et al. The film was pitched as a celebration of animation’s golden era, an honest amalgamation of Disney’s beautiful artwork, Warner’s characterization, and Tex Avery’s humour.